REPORTER: Far away from her tranquil California home, actress and Goop guru Gwyneth Paltrow today, defending herself in a Park City courtroom in Utah. BAILIFF: --so help you God? REPORTER: In a civil suit over her involvement in an alleged skiing hit and run collision. - Did you hit and run? - Absolutely not. REPORTER: Paltrow being sued for $300,000 in damages over a February 2016 skiing accident in the upscale Deer Valley resort, involving 76-year-old retired optometrist Dr. Terry Sanderson, who, in a he said, she said lawsuit, claims the actress was skiing out of control, alleging she crashed into him from behind. Paltrow has filed a countersuit for a symbolic $1 and attorneys' fees, claiming it was Sanderson who actually hit her on the slopes. The former doctor says he was left with brain damage and four broken ribs. PROSECUTOR: So you were watching your children when you allege that you were skied directly into your back by someone? - My daughter was down the hill. My son was to my left. So I was skiing. My eyes were not fixated only on my son when Mr. Sanderson skied directly into my back. REPORTER: But her attorneys claim the retiree had several pre-existing medical conditions before the collision. - This is going to come down to credibility. Who is more believable, not just in how they present themself on the stand, but also on their recitation of the actual facts? Does it make sense for these injuries to match up with this type of collision? - This was a-- this was a significant trip for us. It was the first time Brad and I were introducing our kids and doing something together as-- to see if we could blend families. PROSECUTOR: There's an implication that, at the time of this collision, you were distracted. Were you distracted? GWYNETH PALTROW: No. - Were you paying attention to where you were skiing? GWYNETH PALTROW: I was. - Was there anyone in front of you? GWYNETH PALTROW: There was not. REPORTER: The prosecution presented their case over three days, including testimony from an eyewitness. - I looked over, and then about maybe one or two seconds, and then I heard the scream. And then-- and then I see this-- this skier just slam into the back of Terry. REPORTER: Medical experts. - What I believe happened is that he was struck from the left side and that forced him into the ground. REPORTER: And two of Dr. Sanderson's daughters. - He's not able to complete a task from the beginning to end. He gets distracted. I don't know how he-- how he survives, actually. We want to find help for him. And we also need to be compassionate and understanding about what he's gone through. And also realize that when bad things happen, there's a reason for it, that this is not my dad. This is an alternate version of my dad. - Something's terribly wrong. I think we have a lot of healing to do. REPORTER: Today, 50-year-old Paltrow taking the stand in her own defense for the first time, sharing her side of what happened on that day. DEFENSE ATTORNEY: Did you see Mr. Sanderson in front of you? - No, he was behind me. He was uphill of me so he was higher than me. And he pressed whatever of his body against my back when his skis slid between mine. I was worried about my knee, my back hurt. It felt violating to have somebody press their body against my back. I was full of adrenaline. I was really upset. And I'm sorry that I cursed. REPORTER: The actress, also disputing the prosecution's earlier testimony. PROSECUTOR: Your testimony to the jury here today is Mr. Sanderson skied into you. - That is correct. PROSECUTOR: All right. Craig Ramon, you said he's not telling the truth, or you don't believe him. - I don't-- I'm telling you that what he said is not what happened. PROSECUTOR: OK. So in other words, if somebody says something that's not what happened, they're lying. GWYNETH PALTROW: He is not telling the truth. PROSECUTOR: All right. GWYNETH PALTROW: I don't know if he knows he's lying, but I'm telling you what he said is, unfortunately, not the truth. REPORTER: Dr. Sanderson accusing the actress of negligence and skiing away after she left him injured, a charge Paltrow has denied, stating a ski instructor in her group stayed behind on her behalf. PROSECUTOR: And, again, you didn't leave your name, address, contact information. You didn't fill out any paperwork in connection with this accident. - Eric did on my behalf. PROSECUTOR: Right. - In the acting world, that's a world of representatives, you allow somebody to represent you. So when Eric as an accredited Deer Valley ski instructor, said to me, I'll fill out the paperwork, said to me, you can go ahead. REPORTER: The trial bringing cameras from across the country to this courtroom to follow Paltrow's every move. PRESENTER: And the Oscar goes to Gwyneth Paltrow. REPORTER: Paltrow, becoming a household name at the age of 26, in her Oscar-winning performance-- - It was we ourselves did that. REPORTER: --in Shakespeare in Love and starring as Iron Man's assistant-turned-wife, Pepper Potts, in the Marvel Cinematic Universe. - Oh, pus! REPORTER: After decades on-screen, Paltrow launched her wellness empire Goop. That includes an online store, podcast, and its own Netflix show. - Are you guys ready to go out in the field and make a ruckus? - Goop seems to be a wellness brand that Gwyneth Paltrow announced, and it's something that feels very much female forward. But the products that she sells on Goop is yet another extension, I think, of her probably being a little bit out of touch with average American women. She has beauty products that costs more than a grocery bill for a family of four. REPORTER: Despite its success, the company has been under fire for making unsubstantiated health claims about some of its products. In 2018, the brand was ordered to pay $145,000 after falsely claiming an egg-shaped object could help with women's menstrual health. Last week, Paltrow made more waves after this clip from the podcast, "The Art of Being Well" went viral on TikTok. - I have bone broth for lunch a lot of the days. For dinner I try to eat according to paleo so lots of vegetables. It's really important for me to support my detox. REPORTER: The backlash came quick. - Paltrow later explaining she suffers from long COVID and worked with a doctor to focus on anti-inflammatory foods. When it's not her business ventures or choices about her lifestyle, Paltrow's personal life has also come under the microscope. In 2014, she and her then-husband Chris Martin made headlines after calling their decision to split "conscious uncoupling." - I think that is probably the statement that has haunted her ever since she said it. People thought that it was ridiculous. Girl, just say you're getting divorced. I think anybody who's gone through a divorce has probably consciously made the decision to go through that divorce. And I think people just probably thought that statement was a little bit ridiculous. REPORTER: In recent years, she has continued to be a polarizing figure. - A lot of times when she says things that feel very out of place to probably most average American women, it's because that has never been her experience. REPORTER: But she's not without her backers. The actress-turned-entrepreneur has over 8 million followers on Instagram alone, with Goop events often selling out and her products sought after. - So there is a side to her that people are attracted to. - I think that people gravitate to Gwyneth Paltrow for a reason. You know, she seems nice. She seems like a very smart businesswoman. And obviously, she's a very talented actor. REPORTER: Paltrow's team is expected to call up to 16 witnesses, including ski instructors and their own medical experts, with Paltrow's husband and two children expected to take the stand next week. The actress-turned-entrepreneur now facing scrutiny in a courtroom where a jury will decide whether she, or the man suing her, is in the right. - A big thing in this case are the injuries. That's going to be a pivotal question for the jury of eight people to decide. Is it plausible, based on all this science and expertise, that Paltrow was the victim or that Sanderson was the victim? REPORTER: Beyond how the jury decides, Carter says what may actually matter more for Paltrow is the court of public opinion. - Money is not what's at stake for Gwyneth Paltrow, but I do think that it's reputation, and that's important. And that's probably a reason why she's showing up in court every day. Because her reputation absolutely is at stake.